Projectile-firing weapons have been in use at least since the end of the upper Paleolithic period, when archery (the “bow and arrow”) had been invented. A bow is a projectile-firing weapon in which at least one flexible member creates tension in an attached line, which line may be drawn, flexing the member, and then released to propel a projectile known as an arrow by the elastic rebound of the member and line. In modern warfare, firearms and ballistic missiles use propellants to accelerate projectiles at much higher speeds and to strike distant targets, some of which may be difficult, or even impossible, to view with the naked eye. To capitalize on those capabilities and help direct such projectiles to their distant targets, targeting science has been developed.
A wide variety of aiming devices, known as “sights,” have been developed, and allow a user to aim a projectile weapon at a target using the user's vision to align the two. For example, a rifle-mounted telescopic sight (a.k.a. “scope”) allows a marksman to target distant subjects, typically including the use of optic lenses and a superimposed reticle in the form of crosshairs meeting at a point associated with a point of impact of the projectile (“Impact Point”). Using scopes mounted on high-powered, long-range rifles, highly skilled military and police marksmen, known as snipers, may successfully target and hit subjects at an effective range above 1,000 meters.
However, environmental and user factors can greatly impact the accuracy of rifle and other projectile weapon fire, especially in the instance of ballistic projectiles from handheld weapons. These factors include, but are not limited to: 1) air density, 2) wind velocity, 3) humidity, 4) visibility, 5) air quality, 6) elevation from subject, 7) ambient temperature, 8) hand and body tremor of the user, 9) shake and misalignment due to trigger pull, 10) flinching due to shot anticipation or environmental activity, 11) movement due to breathing, 12) movement due to heartbeat, 13) errant movements, 14) eye shift not addressed by the sight (parallax effect), 15) environmental structural changes or nudges (e.g., sand bag or tripod sinking, nudge from fellow soldier), 16) changes or states of change of any of the above factors, and 17) subject or other more general environmental movement. At longer firing ranges, the impact of these environmental and user factors, and resulting targeting inaccuracy, can be exponentially amplified. But greater ranges are beneficial, because they allow a sniper to maintain a safe distance from enemy forces and remain undetected. If snipers are located, critical missions may fail, and, in military campaigns, snipers may be captured and assassinated.
Advanced reflecting and collimating sights, such as “red dot” sights, are designed to provide rapid acquisition and targeting with both eyes open and observing the entire environment as well as sight components. Such sights may also reduce or substantially eliminate the parallax effect that occurs when the shooter shifts eye position relative to the reticle of a scope or iron sights.